Glycated proteins and advanced glycation end products (AGE) contribute to cellular damage, for example, diabetic tissue injury. This can occur by at least by two major mechanisms: modulation of cellular functions through interactions with specific cell surface receptors, and alteration of the extracellular matrix leading to the formation of protein cross-links. Studies suggest that glycated protein and AGE interactions with cells promote inflammatory processes and oxidative cellular injury. AGE increases lipoprotein oxidisability and atherogenicity. Further, AGE binding to matrix proteins induces synthesis of IL-1, TNFa, VCAM-1, Heme oxygenase, insulin like growth factor, IL-6 and activates NF-?B. Diseases for which glycated protein and AGE accumulation is a suspected etiological factor include, but are not limited to, vascular complications of diabetes, microangiopathies, renal insufficiency, and Alzheimer's disease.
The exact mechanism by which high plasma glucose causes microvascular damage, as seen in diabetes, are not completely understood. One potential mechanism by which hyperglycemia can be linked to microangiopathies is through the process of non-enzymatic glycation of critical proteins. Non-enzymatic glycation of critical proteins is discussed in Nonenzymatic glycosylation and the pathogenesis of diabetic complications, Ann. Intern. Med., 1984(101)527-537; Advanced glycation end products up-regulate gene expression found in diabetic glomerular disease, Proc. Natl. Acad. Sci. USA., 1994 (91)9436-40; Expression of advanced glycation end products and their cellular receptor RAGE in diabetic nephropathy and nondiabetic renal disease, J. Am. Soc. Nephrol., 2000 (11)1656-66; and Activation of receptor for advanced glycation end products: a mechanism for chronic vascular dysfunction in diabetic vasculopathy and atherosclerosis., Circ. Res., 1999 (84)489-97).
Non-enzymatic glycation, i.e., the linking of proteins with glucose, leads to the formation of glycated proteins. The first step in this glycation pathway involves the non-enzymatic condensation of glucose with free amino groups in the protein, primarily the epsilon-amino groups of lysine residues, forming the Amadori adducts. These early glycation products can undergo further reactions such as rearrangements, dehydration, and condensations to form irreversible advanced glycation end products (AGE). These are a highly reactive group of molecules whose interaction with specific receptors on the cell-surface that may lead to pathogenic outcomes. Accumulation of glycated proteins have been demonstrated in the basement membrane of patients with diabetes and are thought to be involved in the development of diabetic nephropathy and retinopathy. See Immunohistochemical localization of glycated protein in diabetic rat kidney., Diabetes Res. Clin. Pract., 1990(8)215-9; and Role of Amadori-modified nonenzymatically glycated serum proteins in the pathogenesis of diabetic nephropathy., J. Am. Soc. Nephrol., 1996(7)183-90. See Inhibitors of AGE formation, such as aminoguanidine, have been shown to block the formation of AGE and prevent development of diabetes complications, including diabetic retinopathy (Aminoguanidine prevents diabetes-induced arterial wall protein cross-linking, Science, 1986(232)1629-1632; Prevention of cardiovascular and renal pathology of aging by the advanced glycation inhibitor aminoguanidine, Proc. Natl. Acad. Sci. USA., 1996(93)3902-7; and Potential benefit of inhibitors of advanced glycation end products in the progression of type II diabetes: a study with aminoguanidine in C57/BLKsJ diabetic mice., Metabolism, 1998(47)1477-80.
One characterized AGE receptor is RAGE, receptor for AGE. See Activation of receptor for advanced glycation end products: a mechanism for chronic vascular dysfunction in diabetic vasculopathy and atherosclerosis, Circ. Res. 1999(84)489-97; and Roles of the AGE-RAGE system in vascular injury in diabetes., Ann. NY Acad. Sci. 2000 (902)163-70; discussion 170-2. Several in vitro and in vivo studies demonstrate that blocking RAGE either by antibodies or by adding a soluble form of the receptor inhibits diabetic vasculopathy including diabetic atherosclerosis. See Receptor-mediated endothelial cell dysfunction in diabetic vasculopathy. Soluble receptor for advanced glycation end products blocks hyperpermeability in diabetic rats., J. Clin. Invest., 1996(97)238-43; Advanced glycation end products interacting with their endothelial receptor induce expression of vascular cell adhesion molecule-1 (VCAM-1) in cultured human endothelial cells and in mice. A potential mechanism for the accelerated vasculopathy of diabetes., J. Clin. Invest., 1995(96)1395-403; and Suppression of accelerated diabetic atherosclerosis by the soluble receptor for advanced glycation endproducts, Nat. Med. 1998(4)1025-31. Other than AGE, RAGE appears to mediate the binding of several other ligands that are involved in normal physiology as well as pathology. See Blockade of RAGE-amphoterin signalling suppresses tumour growth and metastases, Nature, 2000(405)354-60; RAGE mediates a novel proinflammatory axis: a central cell surface receptor for S100/calgranulin polypeptides, Cell, 1999(97)889-901; and Amyloid-beta peptide-receptor for advanced glycation end product interaction elicits neuronal expression of macrophage-colony stimulating factor: a proinflammatory pathway in Alzheimer disease, Proc. Natl. Acad. Sci., USA., 1997(94)5296-301. Thus, merely blocking RAGE might have other unintended consequences. Moreover, since blocking RAGE could lead to accumulation of AGE in circulation, the long-term effects of blocking RAGE are unknown and may be more harmful than the pathology sought to be treated.
One useful method to block AGE effects would be to develop inhibitors that block AGE induced signaling. See Activation of the receptor for advanced glycation end products triggers a p21 (ras)-dependent mitogen-activated protein kinase pathway regulated by oxidant stress, J. Biol. Chem., 1997(272)17810-4; and Cell activation by glycated proteins; AGE receptors, receptor recognition factors and functional classification of AGEs., Cell. Mol. Biol.(Noisy-le-grand), 1998(44)1013-23. However, the sequence of these signaling events leading to inflammation is not clear. Accordingly, what is needed are compounds that can block AGE-induced activities, particularly AGE-induced inflammation, or more particularly, AGE-induced signaling events.
Other chronic conditions for which adequate and effective therapies do not exist are treatments of antiproliferative disorders. Smooth muscle cell (SMC) hyperplasia is an important factor in the development of atherosclerosis and also is responsible for the significant number of failure rates following vascular procedures such as angioplasty and coronary artery bypass surgery. See, The comparative pathobiology of atherosclerosis and restenosis. Am. J. Cardiol. 86:6H-11H (2000); and Restenosis: a challenge for pharmacology. Trends Pharmacol Sci. 21:274-9. In the normal vessel, SMC are quiescent, but they proliferate when damage to the endothelium occurs. Naturally occurring growth modulators, many of which are derived from the endothelium, tightly control SMC proliferation in vivo.
Abnormal vascular smooth muscles cell (VSMC) proliferation may contribute to the pathogenesis of vascular occlusive lesions, including atherosclerosis, vessel re-narrowing after successful angioplasty (restenosis), and graft atherosclerosis after coronary transplantation. VSMC is discussed in The comparative pathobiology of atherosclerosis and restenosis. Am. J. Cardiol. 86:6H-11H; and Smooth muscle migration in atherosclerosis and restenosis. J Clin Invest. 100:S87-9. Many humans and animals have limited lifespans and lifestyles because of such conditions. Currently there are no known effective pharmacological treatments available that control these occlusive pathologies, particularly restenosis.
Percutaneous coronary artery intervention (PTCA) procedures are the most common in-patient hospital procedure in the United States. According to the American Heart Association, about one-third of the patients that undergo balloon angioplasty have restenosis of the widened segment within approximately six months. It may be necessary to perform another angioplasty or coronary artery bypass surgery on restenosed arteries. A key feature of restenosis is an injury response that results in activation of an inflammatory cascade and remodeling of the cells both inside and outside the carotid artery wall. This includes excessive growth of connective tissue and smooth muscle into the lumen of the artery known as neointimal hyperplasia. Currently there are no effective pharmacological treatments available that control the pathogenesis of vascular occlusive lesions, such as, but not limited to, arteriosclerosis, atherosclerosis, restenosis, and graft atherosclerosis after coronary transplantation. Identification of effective therapeutics with minimal side effects will restore quality of life without requiring additional surgical procedures such as coronary artery bypass surgery.
Smooth muscle cell (SMC) hyperplasia is a major event in the development of atherosclerosis and also may contribute to failure rates following vascular procedures such as angioplasty and coronary artery bypass surgery. In the normal vessel, SMC are quiescent, but they proliferate when damage to the endothelium occurs. Naturally occurring growth modulators, many of which are derived from the endothelium, tightly control SMC proliferation in vivo. Accordingly, there is a need for methods and compositions for the alteration of gene expression in arterial wall cells to inhibit thrombosis and SMC proliferation. In particular, what is needed are methods and compositions that inhibit SMC proliferation and related intimal hyperplasia.
U.S. Pat. No. 6,028,088 is directed to specific thiazolidinedione compounds, which are described as antiproliferative, anti-inflammatory and antiinfective agents. According to the disclosure, these specific compounds are used in the treatment of certain endocrine diseases, malignant, and non-malignant proliferative diseases, and cardiovascular disorders.
Thus, there is a need for treatments of vascular occlusive pathologic conditions, and particularly, restenosis. Since occurrence is frequent, the currently available treatments are costly and the conditions are refractory to many pharmacological therapies. The mechanisms involved in the control of vascular conditions related to SMC function are not clear and no conventional preventive therapy against SMC activation is available. Accordingly, methods and compositions for treatment and prevention of vascular occlusive conditions are needed. In particular, methods and compositions to prevent and treat restenosis following treatments of vascular tissues are needed. The present invention is directed to overcoming these and other deficiencies in the art.